Tire with quadrangular studs

ABSTRACT

The invention relates to a studded air-filled vehicle tire having a rolling direction and comprising a rubber tread with pattern blocks and grooves that-separate the blocks. Premade stud holes are arranged in the tread. Anti-slip studs each include a hard cermet piece that has a substantially quadrangular shape with diagonal dimensions are in at least part of the stud holes. At least part of the anti-slip studs arranged in the stud holes are orientated so that one of the diagonal dimensions of the hard cermet piece is located in the rolling direction or forms an angle, not larger than a toe-out angle with respect to the rolling direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/704,217, filed Nov. 4, 2003, which claims priority from FinnishApplication No. 20021966, filed on Nov. 4, 2002, both of which areherein incorporated by reference in their entirety.

FIELD

The invention relates to a studded air-filled vehicle tire with arolling direction and a rubber tread with pattern blocks and groovesseparating the blocks, as well as to tread anti-slip studs having aninner head and an outer head, and a total length therebetween. Each ofthe anti-slip studs comprises a body having a bottom flange and a shankelement extending outwards thereof, with the outer head of the anti-slipstud having a polygonal contact surface.

BACKGROUND

The publication DE-23 42 743 describes an ice stud designed for wintertires on vehicles. The ice stud comprises an element made of a singlematerial and being rectangular in cross-section. The shape of the icestud is substantially the same along the whole length of the anti-slipelement, and the only exceptions are the narrowing bevels arranged inthe inner head inside the tire, the notches made in the stud shank, andthe short X-shape of the outer stud head. A stud designed in thisfashion is by a slight force pressed deeper in the tire and tends toincline excessively in the tire tread during speed changes, such asduring braking or acceleration, as well as during changes in direction,which results in a weak holding power and hence in a weak grip on aslippery road surface. These kinds of ice studs are easily detached fromthe tire tread during usage. The publication mentions a decrease in thewearing of the road surface as the only objective of the disclosed icestud.

The publication JP-58-012806 describes a completely ceramic spike forwinter tires. The spike is a polygon in cross-section, with the contactsurface of the spike tip being particularly polygonal. According to thedrawings of the publication, the contact surface of the spike tip iseither a sharp-angled quadrangle or an octagon. The spike also includesa bottom flange made of the same ceramic material, with the same shapeas the respective shape of the contact surface of the tip.

According to the publication JP-58-012806, the disclosed design ischosen primarily because of the manufacturing technique. But, it ismaintained that the strength and grip of the spike are also improved incomparison with a spike that is round in cross-section, but otherwisehas the same type of structure. In the publication JP-58-012806, thespike material is mainly composed of aluminum oxide Al₂O₃, and thedurability of this type of material is not sufficient in practice. Thistype of spike is strongly inclined when driving, particularly if thetire tread is made of a relatively soft rubber, as is the trendnowadays, which means that the grip is remarkably reduced and the spikesmay even become detached. If a spike of this type is made of asufficiently hard, impact-resistant and wear-resistant hard metal, theweight of the anti-slip element becomes remarkably heavy, which meansthat the wearing of the road surface is intensive and the rubber treadof the tire is easily damaged. The design according to the publicationJP-58-012806 makes it difficult to install spikes by automatic devices.The design also results in a swift tearing of the tire tread in thevicinity of the spike when driving, which, as a consequence, can causethe spikes to fall off.

The publication US-2002/0050312 discloses a studded winter tire.According to the publication, the stud has an elongate bottom part witha shape other than round such that the shape has a lengthwise axis. Thestud also has an elongate top part other than round such that the shapealso has a lengthwise axis. The lengthwise axes of the bottom part andtop part are mutually reversed, so that the lengthwise axis of the toppart and the lengthwise axis of the bottom part together close an angleother than zero, which advantageously is within the range 65°-115°. Theshape of the bottom part and top part of the stud is nearly an ellipse,or an oblong shape resembling an ellipse. According to the publication,this type of stud is shot in the tire tread in a non-vulcanized state byinjection tubes, with the cross-sectional shape of the tubescorresponding to the shape of the studs. The studs are oriented withinthe tread so that in the middle of the tire rolling surface, thelengthwise axes of the top parts of the studs are in a position parallelto the tire axis and the lengthwise axes of the bottom parts of thestuds are arranged in the circumferential direction of the tire. At theedges of the tire rolling surface, the lengthwise axes of the top partsof the studs advantageously form an angle of 45° with respect to thecircumferential direction of the tire, and the lengthwise axes of thebottom parts of the studs advantageously form an angle of 25° withrespect to the circumferential direction of the tire.

When the studded tire disclosed in the publication US-2002/0050312 ismade ready, it may function relatively well, but the manufacturing isproblematic. Studs designed in this way cannot be reliably turned in theright position in automatic installation machines and the studs may endupside down in the injection tubes. Moreover, studs designed in this wayalso easily stick to some part of the automatic installation machines.Further, the vulcanization of tires already having installed studs isextremely difficult and expensive and results in a large number ofdiscarded tires in the production process.

The publication WO-99/56976 discloses an anti-skid spike with a hardcermet piece that has a geometric cross-sectional shape, a limitednumber of symmetry levels and a changing cross-sectional area from theouter head to the inner head such that the hard cermet piece expandstowards the bottom flange of the spike. The publication mentions severaldifferent cross-sectional shapes of the hard cermet piece, such as atriangle, a rectangle, an ellipse, a semi rectangle, a semicircle, aquadrangle, and an octagon, with all such shapes particularly equal insignificance.

As regards the shape of the bottom flange of the anti-skid spike, it isonly said that it may be asymmetrical with respect to one lengthwiseplane with a length and a width that are mutually different. Accordingto the drawings of the publication, the bottom flange includes twoopposite straight sides, either in parallel or at a sharp angle withrespect to each other. It is also mentioned that intermediate shapesbetween these two are possible, but the specification does not offer amore detailed description, only a general remark. Neither of the shapesof the sides of the bottom flange are quadrangles.

The publication WO-99/56976 also recommends the use of a rib in thelengthwise direction of the spike, but without a top bowl.

Further, as shown in the drawings, the longer dimension of the bottomflange of the publication WO-99/56976 can be positioned either in thecircumferential direction of the tire, in which case it is suited tourban driving as described in the publication, or perpendicular to thecircumferential direction, in which case it is suited to driving oncountry roads as described in the publication.

SUMMARY

As will be described in more detail below, disclosed herein haveembodiments of an air-filled vehicle tire provided with anti-slip studsthat facilitate an excellent grip on a slippery road surface and shouldnot have a tendency to fall off even during intensive accelerationand/or braking.

According to some embodiments, a tire with anti-slip studs is disclosedthat would have an optimal wear resistance.

According to yet other embodiments, a tire with anti-slip studs can bestudded by automatic studding machines in a process that is as free oferrors as possible.

In other embodiments, a tire can have stud holes made to be ready foruse as holes or otherwise by conventional and effective productionmethods. The stud holes can then be used to install studs that incross-section are other than round. The studs can be orientatedaccording to the needs of the situation, i.e. certain directions of thecross-sectional shape of the studs could be in certain predeterminedpositions with respect to the circumferential direction or axialdirection of the tire.

The above described problems are solved and the above defined advantagesrealized by a vehicle tire provided with anti-slip studs as describedherein.

It has now been surprisingly found out that (i) by replacing thetraditionally cylindrical hard cermet tip of an anti-slip stud with ahard cermet piece that is quadrangular in cross-section; (ii) byreplacing the traditionally round bottom flange of the stud with aquadrangular bottom flange; and (iii) by arranging the stud in thevehicle tire tread so that one diagonal of the hard cermet piece that isquadrangular in cross-section is substantially arranged in thecircumferential direction of the tire, the grip of the studded tire isclearly-improved in comparison with tires that are provided with aconventional stud having a round hard cermet piece. This is because thestud tips of the present disclosure make a wider adhesion groove in anicy surface or the like than conventional studs. These advantages arerealized without increasing the weight of the anti-slip studs incomparison with prior art studs.

Likewise, it has surprisingly been discovered that by replacing thetraditionally round bottom flange of the stud body by a bottom flangethat is quadrangular in the direction perpendicular to the stud length,the studs are easily and without difficulty adjusted in the tire studholes by automatic installation machines provided with four jaw fingersor even with only three jaw fingers. Moreover, the studs are easily andwithout difficulty adjusted in a desired orientation with respect to thecircumferential direction of the tire or the axial direction of thetire, for instance in the above described diagonal circumferentialdirection.

In certain embodiments, the studs can provide one or more of thefollowing additional advantages: (i) the inclination of the anti-slipstuds is reduced under the holding forces because the flange, i.e. thediagonal, is longer in the direction of a possible inclination; (ii) theturning of the anti-slip studs is reduced; and (iii) the wearing of thetire rubber is reduced. In specific implementations of a stud having arelatively wide top bowl in the stud shank, which top bowl is preferablyseparated from the bottom flange by a neck portion, the inclination ofthe stud is further reduced.

The foregoing and other features and advantages of the embodiments ofthe present disclosure will become more apparent from the followingdetailed description, which proceeds with reference to the accompanyingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 3A illustrate respective embodiments of anti-slip studs attwo orientations with each stud having a quadrangular hard cermet pieceand bottom flange. The stud of FIG. 1A is positioned on the tire in thevicinity of the first shoulder, e.g., at point I of FIG. 4, and the studof FIG. 3A is positioned on the tire in the vicinity of the second tireshoulder, e.g., at point III of FIG. 4. The embodiments of theorientations are realized by using a second installation method as willbe described in more detail.

FIGS. 1B and 3B illustrate respective embodiments of anti-slip studs attwo orientations with each stud having a quadrangular hard cermet pieceand bottom flange. The stud of FIG. 1B is positioned on the tire in thevicinity of the first shoulder, e.g., at point I of FIG. 4, and the studof FIG. 3B is positioned on the tire in the vicinity of the second tireshoulder, e.g., at point III of FIG. 4. The embodiments of theorientations are realized by using a first installation method as willbe described in more detail.

FIG. 2 illustrates an embodiment of an anti-slip stud at a particularorientation with the stud having a quadrangular hard cermet piece andbottom flange. The stud of FIG. 2 can be positioned on the tire nearerto the center regions of the tire width than at points I and III of FIG.4, e.g., at point II of FIG. 4. Alternatively, the anti-slip stud ofFIG. 2 can be positioned on the tire at various other regions of thetire width, such as, for example, at points I and III of FIG. 4.

FIG. 4 is a general illustration of the tread of an air-filled vehicletire showing positions of anti-slip studs as seen from the outside ofthe tire and a direction corresponding to direction V as indicated inFIGS. 5, 12A, 12B and 13A.

FIG. 5 illustrates an axonometric view of another embodiment of ananti-slip stud for use in a studded tire and having a quadrangular hardcermet piece and bottom flange.

FIGS. 6-10 each illustrate a top plan view of respective embodiments ofan anti-slip stud to be used in a studded tire and having a quadrangularhard cermet piece and bottom flange.

FIGS. 11A and 11B illustrate respective embodiments of a stud holehaving an oval part and arranged in the studded tire. The oval part ispositioned with respect to the circumferential direction of the tire. InFIG. 11A, the stud hole is positioned in the vicinity of the tireshoulders, e.g., at points I and III of FIG. 4, and in FIG. 11B, thestud hole is positioned nearer to the center regions of the tire width,e.g., at points II of FIG. 4.

FIG. 12A illustrates a longitudinal cross-section of either the studhole of FIG. 11A or FIG. 11B as seen along the plane VI-VI shown inFIGS. 11A and 11B.

FIG. 12B illustrates a longitudinal cross-section of either the studhole of FIG. 11A or FIG. 11B as seen along the plane VII-VII shown inFIGS. 11A and 11B.

FIG. 13A illustrates a longitudinal cross-section of another embodimentof a stud hole having round parts taken along a vertical plane. The studhole can be arranged in the studded tire at various locations on thetire, e.g., at points I, II and III of FIG. 4.

FIG. 13B illustrates a top plan view of the stud hole of FIG. 13A.

FIGS. 14 and 15 each illustrate a top plan view of a respective one oftwo other embodiments of a stud hole having an oval bottom shape andrespective top parts having the shapes shown.

DETAILED DESCRIPTION

FIG. 4 illustrates a typical tread pattern of a studded, air filledvehicle tire. The air-filled vehicle tire comprises, among other things,a tire housing (not illustrated), a tread 20 made of rubber and studholes 18 in the tread created during the vulcanization of the tire, andanti-slip studs 1 in at least some of the stud holes. As is well known,in the tread 20, also called the wear surface, there are grooves 16 andpattern blocks 17. The anti-slip studs are typically attached in thepattern blocks. The pattern blocks can also have fine grooves, butbecause the invention does not relate to the tread as such, the designof the tread is not explained in more detail. For an optimal holdingcapacity of the tire, the hardness of the rubber quality in the tread 20is relatively low, advantageously of the order 55-60 Shore A. Thestudded tire illustrated in FIG. 4 has a given rolling direction P, butanti-slip studs according to the invention can also be arranged in tireswith a rolling direction that is either one of the oppositecircumferential directions, as shall be explained in more detail below.

Referring to FIG. 5, the anti-slip studs 1 arranged in the tread have aninner head 14, i.e. a head that points towards the axial line of thetire and is set deeper in the tread 20, an outer head 15, i.e. a headthat is set in the region of the outer surface of the tire tread or inthe vicinity of the region, and a total length L1 extending from theinner head and the outer head. Each of the anti-slip studs comprises abody 3 provided with a bottom flange 4 and a shank element 5 pointingoutwards of the body.

Referring now to FIGS. 13A and 13B, the premade stud holes 18 arrangedin the tread 20 can, according to one embodiment, be substantiallycircular in cross-section. In such an embodiment, typically both thebottom part 25 of the stud hole, in which bottom part the bottom flange4 of the anti-slip stud is set, is round, and also the top part 26 ofthe stud hole, in which the top bowl 6 of the anti-slip stud is set, isround. In other embodiments, the cross-sectional shape of the top part26 is other than round (see FIGS. 14 and 15).

Referring now to FIGS. 11A, 11B, 12A and 12B, according to anotherembodiment, the premade stud holes 18 of the tread 20 can have a bottompart 25 that is oval or elongate in cross-section. The oval shape has alarger transverse dimension W4 and a smaller transverse dimension W3 indirections that are perpendicular to the depthwise direction of thehole, i.e., the direction of the stud total length L1. Some stud holesaccording to this embodiment can belong to a first group J1 _(A) and/orJ1 _(B) of stud holes located nearer to the tire shoulders and formed inthe tread of the tire such that the larger transverse dimension W4 ofthe oval bottom part 25 of each of the stud holes 18 are substantiallyin parallel with the tire rolling direction P, as is shown in FIG. 11A.Some other stud holes according to this embodiment can belong to asecond group J2 of stud holes located nearer the center regions of thetire and formed in the tread of the tire such that the larger transversedimension W4 of the oval bottom parts 25 of the stud holes 18 aresubstantially perpendicular to the tire rolling direction P, as is shownin FIG. 11B.

Similarly, the short transverse dimension W3 of the oval bottom part ofeach of the stud holes in the vicinity of the tire shoulders, e.g., thestud hole 18 shown in FIG. 11A, is substantially parallel with the axialline of the tire. The short transverse dimension W3 of the oval bottompart of each of the stud holes in the tire regions located in the centerparts of the tire width, e.g., the stud hole 18 shown in FIG. 11B, issubstantially parallel with the rolling direction P.

In some embodiments, the ratio of the longer transverse dimension W4 ofthe bottom part 25 to the shorter transverse dimension W3, i.e. W4:W3,is at least 1.05, but not more than 2.

The cross-sectional area A_(H) of the stud holes is smaller than thecross-sectional area of the studs. More precisely, the cross-sectionalarea of the bottom part 25 of the stud holes is smaller than across-sectional area A4 of the bottom flange 4 of the anti-slip studs,and the cross-sectional area of the top part 26 of the stud holes issmaller than a cross-sectional area A6 of the top bowl 6 of theanti-slip studs. Accordingly, the anti-slip studs 1 are set tightly inthe holes 18.

Referring back to FIG. 5, the top bowl 6 of the body 3 of the anti-slipstud 1 has transverse dimensions D5, D6 perpendicular to the length ofthe anti-slip stud and a top bowl cross-sectional area A6 that isperpendicular to the length L1. The top bowl 6 may have a round shape asviewed perpendicular to said length of the anti-slip stud. In someimplementations, as shown in FIG. 5, the transverse dimensions D5 and D6are equally large. In other implementations, the top bowl 6 has anoblong shape such that the transverse dimensions D5 and D6 are unequal,or the top bowl has a polygonal shape such that the transversedimensions D5 and D6 are equally large or not equally large.

A neck portion 7 is arranged between the top bowl 6 and the bottomflange 4. The neck portion 7 has a cross-sectional area A7 perpendicularto the length L1 of the anti-slip stud that is substantially smallerthan the cross-sectional area A6 of the top bowl 6 and thecross-sectional area A4 of the bottom flange 4. The neck portion 7clearly separates the top bowl 6 from the bottom flange 4.

Each anti-slip stud 1 comprises a hard cermet piece 2 made of adifferent material than the body 3. The hard cermet piece 2 is placedinside the body 3 and protrudes out of the body's outer head 15. Thehard cermet piece 2 also has a substantially quadrangular shape in adirection perpendicular to the stud length L1.

The typical length L1 of the studs for passenger car tires is between 10mm and 11 mm, for delivery van tires between 11 mm and 13 mm, for trucktires between 14 mm and 17 mm. and for tires for heavy machinery, suchas loaders, road machines etc., between 17 mm and 20 mm. The rubbersurrounding the stud body 3 in the tread 20 supports the stud and holdsit in the right position, i.e. substantially perpendicular to the treadrolling surface.

The quadrangular hard cermet piece has diagonal dimensions D3 and D4 ina direction perpendicular to the stud length L1. At least part of theanti-slip studs 1 inserted in the premade stud holes 18 are orientatedso that one of the diagonal dimensions D3 or D4 of the hard cermet pieceis located in the tire rolling direction P, as shown in FIG. 2, or formsan angle that is not larger than a toe-out angle K with said rollingdirection P, as shown in FIGS. 1A, 1B, 3A, and 3B. It should beunderstood that the studs 1 can, according to the needs of thesituation, be installed in either all of the stud holes 18 arranged inthe tread 20, or only in part of the stud holes. Likewise, it should beunderstood that each anti-slip stud 1 installed in the tread 20 isorientated either (1) so that the diagonal dimensions D3, D4 of the hardcermet pieces are located in said rolling direction P; (2) so that theyform, with respect to said direction, an angle that is not larger thanthe toe-out angle K; or (3) in some other way. According to someembodiments, the toe-out angle K is smaller than 30°. In specificimplementations, the toe-out angle K is not larger than 20° and in otherimplementations, the toe-out angle K is not larger than 15°. In certainimplementations, it may be advantageous to use toe-out angles K that arenot larger than 10°.

The hard cermet piece 2 is arranged inside the stud body 3. The cermetpiece 2 has a length L2 that is smaller than the total length L1 of theanti-slip stud, a cross-sectional area A2 that is smaller than thecross-sectional area A7 of the stud neck portion 7 and substantiallysmaller than the cross-sectional areas A6 and A4 of the stud top bowl 6and bottom flange 4, respectively.

The side surfaces 10 a, 10 b, 10 c, 10 d of the quadrangular hard cermetpiece 2 can be (1) convex, as shown, for example, in FIG. 10; (2)concave, as shown, for example, in FIG. 8, and have a curvature R4; or(3) straight, as shown, for example, in FIGS. 1A-3B, 5-7 and 9. Theabove mentioned diagonal dimensions D3, D4 of the hard cermet piece 2are typically equally large or nearly equally large, such as shown inFIGS. 1A-3B, 5 and 7-10. In such embodiments, the shape of thequadrangular hard cermet piece is mainly a square or a rectangle.

In other embodiments, the diagonal dimensions D3, D4 may also bemutually different, such as shown in FIG. 6, such that the shape of thequadrangular hard cermet piece is mainly a lozenge or a parallelepiped.

The described shape definitions, such as square, rectangle, lozenge andparallelepiped, are also applicable to a cermet piece 2 with sides 10 a,10 b, 10 c, 10 d having curvature R4 as long as the side curvature orradius of curvature R4 is substantially larger than the radius of thecircle drawn via the edges, or corners, 11 a, 11 b, 11 c, 11 d of thehard cermet piece. In other words, the shape definitions are applicableas long as both of the diagonal dimensions D3 and D4, which pass from anedge of the hard cermet piece to the opposite edge, are larger than allother connecting lines between the opposite sides 10 a and 10 c, or 10 band 10 d of the hard cermet piece that pass through the intersection ofthe diagonal dimensions D3, D4.

The edges 11 a, 11 b, 11 c, 11 d between the side surfaces of thequadrangular hard cermet piece 2 have a rounding R3 that issubstantially smaller than the curvature R4. In some embodiments, therounding R3 is at least 0.1 mm, but no more than 0.2 mm. The roundingcan prevent the hard cermet piece from splitting. The side surfaces 10a, 10 b, 10 c, 10 d of the quadrangular hard cermet piece have widthsW1, W2 with a mutual difference that is at most the ratio 1.5, in otherwords, W1:W2<1.5.

In specific implementations, such as with tires of passenger cars anddelivery vans, the cross-sectional area A2 of the hard cermet piece isbetween 4.5 mm² and 6 mm². For example, with a hard cermet piece havinga quadrangular or corresponding shape, the widths W1, W2 can be between2.1 mm and 2.5 mm and the diagonals can be between 2.9 mm to 3.6 mm. Insome implementations, the hard cermet piece can have a rectangular shapewith extreme values that somewhat deviate from these. In otherimplementations, such as with tires of trucks, the cross-sectional areaA2 of the hard cermet piece of the anti-slip studs 1 is between 7 mm²and 9 mm², and with tires of heavy machinery, the cross-sectional areaA2 is between 9 mm² and 13 mm².

By applying the shape and orientation of the hard cermet piece in thetire as described above, there is achieved an excellent holding capacityfor the studded tire in the desired way.

The bottom flange 4 of the anti-slip stud 1 has a substantiallyquadrangular shape in a direction perpendicular to the length L1 of thestud, diagonal dimensions D1 and D2, and a cross-sectional area A4 in adirection perpendicular to the stud length L1. The diagonal dimensionsD1, D2 of the bottom flange 4 can be equally large, such as shown inFIGS. 1A-3B and 5-9, or they can be different in length, such as shownin FIG. 10. In some embodiments, the bottom flange is quadrangular. Inother embodiments, the bottom flange has a lozenge shape. In yet otherembodiments, the bottom flange has a rectangle shape.

The diagonal dimensions D1, D2 of the bottom flange 4 are eithersubstantially parallel with the diagonal dimensions D3, D4 of the hardcermet piece, such as shown in FIGS. 1A, 2, 3A, 5-6 and 8, or they forma toe-out angle K with respect to the diagonal dimensions D3, D4 of thehard cermet piece, such as shown in FIGS. 1B, 3B, 7 and 9-10. The bottomflange sides 9 a, 9 b, 9 c, 9 d can have a curvature R2 and be convex,such as shown in FIGS. 5, 6 and 10, or concave, such as shown in FIG. 9.As an alternative, the bottom flange sides 9 a, 9 b, 9 c, 9 d can bestraight, such as shown in FIGS. 1A-3B and 7-8.

The above described shape definitions of square, rectangle and lozengealso apply to shapes provided with sides 9 a, 9 b, 9 c, 9 d that have acurvature R2, as long as the curvature or radius of curvature R2 of thesides is substantially larger than the radius of a circle drawn throughthe bottom flange edges 8 a, 8 b, 8 c, 8 d (see, e.g., FIG. 9). Thus,both of the above mentioned diagonal dimensions D1 and D2, which passfrom the bottom flange edge to the opposite edge, are larger than allother lines connecting the opposite sides 9 a and 9c or 9 b and 9 d ofthe bottom flange and passing through the intersection of the diagonaldimensions D1, D2.

In addition, the edges 8 a, 8 b, 8 c, 8 d left between said sides of thebottom flange have a rounding R1 that is substantially smaller than thecurvature R2.

By the shape of the bottom flange as described above, the anti-slipstuds are orientated in a desired fashion in the stud holes 18 such thata desired and excellent holding capacity for the studded tire isobtained.

The hard cermet piece is comprised of any sufficiently hard andappropriate known or new, generally sintered metal, such as metalcarbides, metal nitrides, metal oxides etc. In some implementations, thehard cermet piece 2 is made of compounds of known, mainly sinteredcarbides that are typically, but not necessarily, bound by a metalmatrix.

The stud body 3 may be made of a known or new suitable metal alloy, suchas steel or aluminum, or it may be made of a suitable plastic orcomposite material. These materials are provided as examples only.

The hard cermet piece 2 can be attached to the body 3 by a solder joint,adhesive, a cast adhesion or a conical pressure joint depending on,among other things, the body material.

According to some embodiments, the location of the diagonal dimensionsD3, D4 of the hard cermet pieces in the rolling direction P or at anangle with respect to said rolling direction, which angle is not largerthan the toe-out angle K, as described above, is arranged so that one ofthe diagonal dimensions D1 or D2 of the bottom flange is located in saidrolling direction P or forms said toe-out angle K with respect to therolling direction P. In principle, it is maintained that the number ofdifferent orientations of the studs in the tire may be nearly infinite.For example, the toe-out angle K can equal 0°, i.e., when diagonaldimensions D3 or D4 are parallel with the rolling direction P, or equalany of various other possible toe-out angles, such as, for example,K=1°, 2°, 3°, 4° . . . etc. The different orientations of the anti-slipstud with respect to the rolling direction can be realized in manydifferent ways by using the quadrangular shape of the anti-slip studbottom flange 4 in adjusting the stud position.

According to a first embodiment of a stud installation method, allanti-slip studs used in a given tire are, with regards to the directionsor positions of the diagonal dimensions D3, D4 of the hard cermet piecerelative to the diagonal dimensions D1, D2 of the bottom flange 4, ofthe same type. In some implementations, for example, all the studs areof a type where at least one of the diagonal dimensions D3 or D4 of thehard cermet piece is parallel with at least one of the diagonaldimensions D1 or D2 of the bottom flange. More specifically, in certainimplementations, both of the diagonal dimensions D3 and D4 of the hardcermet piece are parallel with the corresponding diagonal dimensions D1and D2 of the bottom flange.

In the first embodiment, the control elements of the installationmachine (not shown) are always arranged in such a position, with respectto the tire tread under operation, that the studs 1 are set in a desiredorientation. The installation method is apparent from FIGS. 1A, 2, 3A.For example, in the case of FIG. 2, the mutually parallel diagonals D3and D1 of the studs are located in the tire rolling direction P, and inthe case of FIGS. 1A and 3A, both of the mutually parallel diagonals D3and D1 are turned to opposite toe-out angles K with respect to therolling direction P. It should be understood that these positions can beachieved by turning the jaws of the installation machine (not shown) inthree different positions between which is formed the toe-out angle.

According to a second embodiment of a stud installation method, theanti-slip studs used in a given tire are, with regards to the directionsor positions of the diagonal dimensions D3, D4 of the hard cermet piecerelative to the diagonal dimensions D1, D2 of the bottom flange 4, of atleast two different types. In at least one of the two types, thediagonal dimension D3 and/or D4 of the hard cermet piece forms a toe-outangle K of a predetermined size with the diagonal dimension D1 and/or D2of the bottom flange.

In the second embodiment, the control elements of the installationmachine can be arranged in a standard position based on the angledifferences between the diagonals of the hard cermet piece and thediagonals of the bottom flange and the corresponding desired toe-outangles K in a finished studded tire. Based on the various regions of thetire tread in which a stud is desirably installed, the desiredorientation of the hard cermet piece is obtained by changing the type ofthe studs to be inserted. The installation method can be understood fromFIGS. 1B and 3B. For example, the studding is carried out by using studsof a first type as shown in FIGS. 2 and 5 and studs of a second type asshown in FIGS. 1B and 3B. The toe-out angle K is formed by means of thestuds illustrated in FIGS. 1B and 3B and installed according to FIGS. 1Band 3B. The diagonal dimensions D1 and/or D2 of the bottom flange of thestuds of the second type are set in the rolling direction P and thediagonals D3 and/or D4 of the hard cermet piece are turned to oppositetoe-out angles K with respect to the rolling direction P, such as shownin FIGS. 1B and 3B.

According to one embodiment, the anti-slip studs 1 may be arranged inthe tread 20 of a vehicle tire in one position only. For example, allstuds are arranged in the position illustrated in FIG. 2, e.g., one ofthe diagonals D3 or D4 of the hard cermet piece 2 is substantially inparallel with the rolling direction P. However, according to otherembodiments, it is more advantageous to arrange the anti-slip studs 1 inthe tire tread 20 in various positions, such as in at least twodifferent positions, or in at least three positions, such as three ofthe positions shown in FIGS. 1A-4. Accordingly, the anti-slip studsarranged on a tire typically constitute at least two first groups J1_(A) and J1 _(B) nearer to the tire shoulders and at least one secondgroup J2 nearer to the center regions of the tire. In this manner, andwhen so desired, the studded tire is made symmetrical in the widthdirection of the tread. It also is possible, however, to use only onefirst group J1 _(A) or J1 _(B) nearer to one of the tire shoulders andat least one second group J2 nearer to the center regions of the tireand to the opposite shoulder. In this manner, and when so desired, thestudded tire is made asymmetrical in the width direction of the tread.It is known in the prior art that the tread pattern proper of the tread20 may, independent of the studding, be either symmetrical orasymmetrical.

According to some embodiments, one set of the diagonal dimensions D3 orD4 of the hard cermet pieces of the anti-slip studs in the first groupsJ1 _(A) and J1 _(B) are located at said toe-out angle K with respect tothe rolling direction P, such as shown in FIGS. 1A, 1B, 3A, 3B and 4,and one set of the diagonal dimensions D3 or D4 of the hard cermetpieces of the anti-slip studs in the second group J2 are locatedsubstantially in parallel with the rolling direction P, such as shown inFIGS. 2 and 4. In any case, the toe-out angles of the cermet pieces ofthe studs in the second group J2 are smaller than in the first group orgroups J1 _(A), J1 _(B).

In some embodiments, with studs in the first groups J1 _(A), J1 _(B),the toe-out angle K of the cermet piece is smaller than the earliermentioned 30°. In some implementations, the toe-out angle K is notlarger than 20°, and in other implementations, the toe-out angle K isnot larger than 15°. In certain implementations, the applied toe-outangles K are not larger than 10°.

With studs of in the second group J2, in some embodiments, the toe-outangles K of the cermet piece is smaller than 15°. In someimplementations, the toe-out angle K is smaller than 10° and in otherimplementations, the toe-out angle K approaches the value 0°.

Although not illustrated in the drawings, in some embodiments, thirdgroups can be located between the first and second groups and naturallybe interlaced with one or both of the above described groups,. Thecermet pieces of the studs in the third group can be oriented atintermediate toe-out angles K with respect to the rolling direction P,such as, for example, angles between 10° and 15°.

For tires having a tread pattern that can be arranged to rotate in anydirection when mounted to a vehicle, i.e., a tire that has a rollingdirection in either one of the two opposite circumferential directions,the toe-out angles K of the studs in the first groups or group can bepointed in any of two directions, i.e., directions outwardly or inwardlyfrom the center line 21 of the tread 20.

On the other hand, for tires having a tread pattern that can be arrangedto rotate in only a single given predetermined rolling direction, i.e. atire that must be arranged in the vehicle so that the rolling directionis always the same when driving forward, a more effective method offorming the toe-out angle can be applied. For example, in the firstgroups J1 _(A) and J1 _(B), the toe-out angles K of one set of thediagonal dimensions D3 or D4 of the hard cermet pieces are pointed, whenseen in the rolling direction P, outwardly from the center line 21 ofthe width of the tread 20. The toe-out angles K open in the rollingdirection P, which points downward in FIGS. 1A, 1B, 3A and 3B, and aredefined as the angles between the diagonals D3 or D4 of the hard cermetpieces and the rolling direction P. The toe-out angles K are alwayslocated outside the rolling-direction line 22 proceeding from a centerline 23 of each anti-slip stud 1, with the toe-out angles K of the studsin group J1 _(A) extending in one direction and the toe-out angles K ofthe studs in the group J1 _(B) extending in the opposite direction.

In some embodiments, there may be several of stud groups, such as, forexample, five stud groups. In such embodiments, the studs 1 belonging tothe group that is located nearest to the shoulders can have the widesttoe-out angle, the middle group does not have any toe-out angle at all,as was explained above, and the studs 1 belonging to the group or groupstherebetween have toe-out angles that are smaller than the studs locatednear the shoulders. In certain implementations, however, it is possibleto arrange the anti-slip studs 1 of the additional groups such that thetoe-out angles of the studs are pointed in different directions thanwhat was explained above.

The first stud groups J1 _(A), J1 _(B) and second stud group J2, i.e.,those regions of the tire tread that are provided with studs fulfillingsaid the above-described conditions, can be mutually fully detached orspaced-apart from each other, or the regions can be exactly bordered byeach other. In practice, for example, it should be most feasible thatthe first groups J1 _(A), J1 _(B) are interlaced with respect to thesecond group J2, such as when these groups are observed in the wayindicated in FIG. 4, i.e., as zones in the width direction that arebordered in the width direction by the outermost studs 1 that fulfillthe toe-out condition of the studs of the respective group. The toe-outcondition is fulfilled if the toe-out angle K has either a given,predetermined value, or the toe-out angle K is within a given,predetermined angle range.

The terms and expressions which have been employed in the foregoingspecification are used as terms of description and not of limitation,and there is no intention, in the use of such terms and expressions, ofexcluding equivalents of the features shown and described or portionsthereof, it being recognized that the scope of the invention is definedand limited only by the claims which follow.

1. A studded air-filled vehicle tire, having a predetermined rollingdirection, and comprising a rubber tread with pattern blocks, groovesseparating said blocks and premade stud holes in said tread, said tirebeing provided with anti-slip studs each with an inner head, an outerhead, and a total length therebetween, said studs being inserted in atleast some of said stud holes, each of said studs comprising: a bodywith a bottom flange and a shank with a top bowl, said bottom flangehaving a substantially quadrangular shape with sides and rounded edgestherebetween and with diagonal dimensions perpendicular to said totallength; and a hard cermet piece of a different material than said body,and protruding out of said outer head, said hard cermet piece having asubstantially square or rhombus shape with substantially equilateralside surfaces, and diagonal dimensions perpendicular to said totallength; and wherein said diagonal dimensions of the bottom flange (i)are substantially parallel to the diagonal dimensions of the hard cermetpiece separate from the bottom flange; or (ii) form a toe-out angle withrespect to the diagonal dimensions of the hard cermet piece; and whereinsubstantially all of the anti-slip studs inserted in the stud holes areorientated so that one of said diagonal dimensions of the hard cermetpieces forms a toe-out angle that is smaller than 10° with respect tothe rolling direction.
 2. A studded tire according to claim 1, whereinsaid diagonal dimensions of the bottom flange are equally large.
 3. Astudded tire according to claim 1, wherein said diagonal dimensions ofthe bottom flange are different from each other.
 4. A studded tireaccording to claim 1, wherein said inserted anti-slip studs have saiddiagonal dimensions of the bottom flange (i) in said rolling direction;or (ii) at said toe-out angle with respect to the rolling direction. 5.A studded tire according to claim 1, wherein said toe-out angles of thediagonal dimensions of the hard cermet pieces are pointed outwardly fromthe center line of the width of the tread, when observed in said rollingdirection.
 6. A studded tire according to claim 1, wherein a pluralityof the anti-slip studs are arranged in an interlacing fashion.
 7. Astudded tire according to claim 1, wherein the top bowl has transversedimensions, and wherein the body comprises a neck portion between saidtop bowl and said bottom flange, the neck portion having across-sectional area that is substantially smaller than thecross-sectional areas of the top bowl and the bottom flange.
 8. Astudded tire according to claim 1, wherein the sides of the bottomflange are straight, convex or concave, and wherein if the sides of thebottom flange are convex or concave, said sides have a curvature largerthan the rounded edges formed between said sides.
 9. A studded tireaccording to claim 1, wherein the top bowl comprises a round shape inthe direction perpendicular to said length of the anti-slip stud,wherein said transverse dimensions are equally large.
 10. A studded tireaccording to claim 1, wherein the top bowl comprises an oblong shape inthe direction perpendicular to said length of the anti-slip stud,wherein said transverse dimensions are different from each other.
 11. Astudded tire according to claim 1, wherein the top bowl comprises apolygonal shape in the direction perpendicular to said length of theanti-slip stud, wherein said transverse dimensions are different fromeach other.
 12. A studded tire according to claim 1, wherein the sidesurfaces of the hard cermet piece are straight, convex or concave, andwherein if the side surfaces of the hard cermet piece are convex orconcave, said side surfaces have a curvature.
 13. A studded tireaccording to claim 1, wherein said diagonal dimensions of the hardcermet piece are substantially equally large.
 14. A studded tireaccording to claim 12, wherein edges between the side surfaces of thehard cermet piece have a rounding that is substantially smaller thansaid curvature of said side surfaces.
 15. A studded tire according toclaim 14, wherein said rounding is between about 0.1 mm and about 0.2mm.
 16. A studded tire according to claim 1, wherein said hard cermetpiece has a piece length that is smaller than the total length of theanti-slip stud.
 17. A studded tire according to claim 1, wherein thebody of the anti-slip stud is made of plastic or metal, and the hardcermet piece is attached to the body by a solder joint, an adhesive, acast adhesion of the body, or a conical pressure joint.
 18. A studdedtire according to claim 1, wherein the material of the hard cermetpieces is sintered carbide.
 19. A studded tire according to claim 1,wherein said premade stud holes in the tread are substantially round incross-section.
 20. A studded tire according to claim 1, wherein saidpremade stud holes in the tread have a bottom part that is an oval incross-section, the oval having a larger transverse dimension and asmaller transverse dimension.
 21. A studded tire according to claim 20,wherein said inserted anti-slip studs comprise at least one first groupnearer to the tire shoulders, and at least one second group nearer tothe tire center regions, and wherein the larger transverse dimension ofthe oval is intended for the anti-slip studs belonging to said firstgroup, the larger transverse dimension being located substantially inthe tire rolling direction.
 22. A studded tire according to claim 20,wherein said inserted anti-slip studs comprise at least one first groupnearer to the tire shoulders, and at least one second group nearer tothe tire center regions, and wherein the larger transverse dimension ofthe oval is intended for the anti-slip studs belonging to said secondgroup, the larger transverse dimension being located in an substantiallyperpendicular direction to the tire rolling direction.
 23. A studdedtire according to claim 20, wherein the ratio of the larger transversedimension to the smaller transverse dimension is at least about 1.05 butnot greater than about
 2. 24. A studded tire according to claim 20,wherein said premade stud holes in the tread have a top part with across-sectional shape that is round.
 25. A studded tire according toclaim 20, wherein said premade stud holes in the tread have a top partwith a cross-sectional shape that is not round.
 26. A studded tireaccording to claim 19, wherein a cross-sectional area of the stud holesin a bottom flange area is smaller than a cross-sectional area of saidbottom flange.
 27. A studded tire according to claim 20, wherein across-sectional area of the stud holes in a bottom flange area issmaller than a cross-sectional area of said bottom flange.
 28. A studdedtire according to claim 19, wherein a cross-sectional area of the studholes in a top bowl area is smaller than a cross-sectional area of thetop bowl of the studs.
 29. A studded tire according to claim 20, whereina cross-sectional area of the stud holes in a top bowl area is smallerthan a cross-sectional area of the top bowl of the studs.
 30. A studdedair-filled vehicle tire, having a predetermined rolling direction, andcomprising a rubber tread with pattern blocks, grooves separating saidblocks and premade stud holes in said tread, said tire being providedwith anti-slip studs each with an inner head, an outer head, and a totallength therebetween, said studs being inserted in at least some of saidstud holes, each of said studs comprising: a body with a bottom flangeand a shank with a top bowl, said bottom flange having a substantiallyquadrangular shape with sides and rounded edges therebetween and withdiagonal dimensions perpendicular to said total length; and a hardcermet piece of a different material than said body, and protruding outof said outer head, said hard cermet piece having a substantially squareor rhombus shape with substantially equilateral side surfaces, anddiagonal dimensions perpendicular to said total length; and wherein saiddiagonal dimensions of the bottom flange (i) are substantially parallelto the diagonal dimensions of the hard cermet piece; or (ii) form atoe-out angle with respect to the diagonal dimensions of the hard cermetpiece; and wherein said anti-slip studs inserted in the stud holes areorientated so that one of said diagonal dimensions of the hard cermetpieces is substantially in said rolling direction.
 31. A studded tireaccording to claim 30, wherein said diagonal dimensions of the bottomflange are equally large.
 32. A studded tire according to claim 30,wherein said diagonal dimensions of the bottom flange are different fromeach other.
 33. A studded tire according to claim 30, wherein saidinserted anti-slip studs have said diagonal dimensions of the bottomflange (i) in said rolling direction; or (ii) at a toe-out angle withrespect to the rolling direction.
 34. A studded tire according to claim30, wherein the top bowl has transverse dimensions, and wherein the bodycomprises a neck portion between said top bowl and said bottom flange,the neck portion having a cross-sectional area that is substantiallysmaller than the cross-sectional areas of the top bowl and the bottomflange.
 35. A studded tire according to claim 30, wherein the sides ofthe bottom flange are straight, convex or concave, and wherein if thesides of the bottom flange are convex or concave, said sides have acurvature larger than the rounded edges formed between said sides.
 36. Astudded tire according to claim 30, wherein the top bowl comprises around shape in the direction perpendicular to said length of theanti-slip stud, wherein said transverse dimensions are equally large.37. A studded tire according to claim 30, wherein the top bowl comprisesan oblong shape in the direction perpendicular to said length of theanti-slip stud, wherein said transverse dimensions are different fromeach other.
 38. A studded tire according to claim 30, wherein the topbowl comprises a polygonal shape in the direction perpendicular to saidlength of the anti-slip stud, wherein said transverse dimensions aredifferent from each other.
 39. A studded tire according to claim 30,wherein the side surfaces of the hard cermet piece are straight, convexor concave, and wherein if the side surfaces of the hard cermet pieceare convex or concave, said side surfaces have a curvature.
 40. Astudded tire according to claim 39, wherein edges between the sidesurfaces of the hard cermet piece have a rounding that is substantiallysmaller than said curvature of said side surfaces.
 41. A studded tireaccording to claim 30, wherein said hard cermet piece has a piece lengththat is smaller than the total length of the anti-slip stud.
 42. Astudded tire according to claim 30, wherein the body of the anti-slipstud is made of plastic or metal, and the hard cermet piece is attachedto the body by a solder joint, an adhesive, a cast adhesion of the body,or a conical pressure joint.
 43. A studded tire according to claim 30,wherein the material of the hard cermet pieces is sintered carbide. 44.A studded tire according to claim 30, wherein said premade stud holes inthe tread are substantially round in cross-section.
 45. A studded tireaccording to claim 30, wherein said premade stud holes in the tread havea bottom part that is an oval in cross-section, the oval having a largertransverse dimension and a smaller transverse dimension.
 46. A studdedtire according to claim 30, wherein said diagonal dimensions of the hardcermet piece are substantially equally large.
 47. A studded air-filledvehicle tire, having a single predetermined rolling direction, andcomprising a rubber tread with pattern blocks, grooves separating saidblocks and premade stud holes in said tread, said tire being providedwith anti-slip studs each with an inner head, an outer head, and a totallength therebetween, said studs being inserted in at least some of saidstud holes, each of said studs comprising: a body with a bottom flangeand a shank with a top bowl, said bottom flange having a substantiallyquadrangular shape with diagonal dimensions perpendicular to said totallength; and a hard cermet piece of a different material than said body,and protruding out of said outer head, said hard cermet piece having asubstantially square or rhombus shape with substantially equilateralside surfaces, and diagonal dimensions perpendicular to said totallength; and wherein said diagonal dimensions of the bottom flange (i)are substantially parallel to the diagonal dimensions of the hard cermetpiece separate from the bottom flange; or (ii) form a toe-out angle withrespect to the diagonal dimensions of the hard cermet piece; and whereinsaid anti-slip studs inserted in the stud holes are orientated so thatone of said diagonal dimensions of the hard cermet pieces forms atoe-out angle that is smaller than 30° with respect to the rollingdirection, and wherein when observed in said single predeterminedrolling direction of the tire, said toe-out angles of the diagonaldimensions of the hard cermet pieces are oriented outwardly from acenter line of the tread.
 48. A studded air-filled vehicle tire, havinga predetermined rolling direction, and comprising a rubber tread withpattern blocks, grooves separating said blocks and premade stud holes insaid tread, said tire being provided with anti-slip studs each with aninner head, an outer head, and a total length therebetween, said studsbeing inserted in at least some of said stud holes, each of said studscomprising: a body with a bottom flange and a shank, said bottom flangehaving a substantially quadrangular shape with diagonal dimensionsperpendicular to said total length; and a hard cermet piece of adifferent material than said body, and protruding out of said outerhead, said hard cermet piece having a substantially quadrangular shapewith diagonal dimensions perpendicular to said total length; and whereinsaid hard cermet piece has an orientation with respect to the bottomflange such that said diagonal dimensions of the bottom flange (i) aresubstantially parallel to the diagonal dimensions of the hard cermetpiece separate from the bottom flange; or (ii) form a first toe-outangle that is smaller than 300 with respect to the diagonal dimensionsof the hard cermet piece; and wherein at least some of the anti-slipstuds inserted in the stud holes are orientated so that one of saiddiagonal dimensions of each respective hard cermet piece (i) is in saidrolling direction, or (ii) forms a second toe-out angle that is smallerthan 30°, with respect to the rolling direction; and wherein on at leastone side of the tire, said inserted anti-slip studs comprise at leastone first group of said anti-slip studs and at least one second group ofsaid anti-slip studs, said orientation of said hard cermet piece withrespect to the bottom flange of each of said studs of said first groupbeing different than said orientation of said hard cermet piece withrespect to the bottom flange of each of said studs of said second group.